For Mobi fans
Mobipocket Creator Home EditionMobiPocket has published the Home Edition: it can convert Word and HTML documents and it has an emulator showing what the final result looks like.
I have not tested it - the price looks quite steep (US$29.95), also considering that iSiloX comes for free (though only a reader with limited functionality is free).
[Source: MobileRead brings a short article describing more features.]